Temperature-Insensitive Fiber-Optic Contact Force Sensor for Steerable Catheters

A steerable catheter with a compact fiber optic sensor for temperature-insensitive contact force measurement is demonstrated. A fiber Bragg grating (FBG) is used as the sensor, which is very small and can be fixed on the outer arc of a steerable catheter, such that it does not occupy any space inside the catheter. Contact force sensing performance under various curve diameters during steering is studied and the results show high repeatability. Since the curve diameter during steering is predetermined, accurate contact force measurement can be performed through calibrating the measurement with various steered catheter positions. Different from most conventional FBG contact force sensors, this approach does not require the analysis of FBG reflection spectra. Instead, contact force applied on the catheter tip is determined by the direct measurement of total FBG reflection power, enabling real time, low cost, and compact sensing. Furthermore, the proposed catheter is tested under different temperatures, and temperature-insensitive performance is also obtained.